The Asus Eee Pad Transformer Prime hardly needs an introduction. It's the replacement for the successful Eee Pad Transformer, and like that first model, the Prime works with an optional $149 keyboard dock that turns it into a mobile OS notebook of sorts. The Prime is the world's first quad core tablet (we're not including Windows 7 tablets, which are a very different animal), and it runs on the NVidia Tegra 3 CPU that clocks up to 1.6GHz. The prime is razor-thin (as thin as the iPad 2) and at 1.29lbs., it's currently the lightest 10" tablet. Top that off with a stunning aluminum back that's available in champagne gold and amethyst gray, and a Super IPS + display capable of 600 nits brightness, and you've got Asus' second generation Android tablet.

The Prime came out at the end of December 2011 in extremely limited quantities, and as of early February 2012 it and the companion keyboard dock are still hard to find. Though Asus stated that they were going to make plenty of Transformer Primes so they wouldn't repeat the low stock fiasco that was the original Transformer launch (you couldn't find one in stores for months), it clearly hasn't worked out for them. The tablet currently ships with Android OS 3.2 Honeycomb, but on first boot, it will download and install Android OS 4.0.3 Ice Cream Sandwich. The Prime is the first tablet to get ICS, just as the Samsung Galaxy Nexus was the first phone to run ICS. The Motorola Xoom (Google's reference Android tablet and the first Honeycomb tablet dating back to February 2011) is the second tablet to get ICS, and we expect the new Acer Iconia Tab A200 will be next. Ice Cream Sandwich brings UI improvements and is a good step forward for Android, though it's not as cosmetically different from Honeycomb as it is from Gingerbread for Android phones.

The tablet runs on the quad core Tegra 3 with a gig of RAM and 32 or 64 gigs of internal storage. It has single band WiFi 802.11b/g/n, Bluetooth 2.1 + EDR and a GPS that famously doesn't work very well. If you're serious about using GPS for driving navigation, the Prime isn't a good choice, but in general we'd recommend tablets with embedded 3G/4G for that task. The Prime has an 8 megapixel rear camera and a front 1.2 megapixel video chat camera. Asus says the Prime has stereo speakers, but there's just one speaker grille on the lower right side (when held in landscape mode). If there are two speakers under there, forget about stereo separation.

The keyboard dock adds a full size USB 2.0 port, a full size SD card slot and a secondary battery that increases the tablet's runtime up to 6 hours.

The Troubles, or the Tale of Three Primes

The Prime hasn't been without troubles. Beyond a serious lack of inventory, a delayed release and Asus' removal of the GPS from its specs list because the GPS doesn't work well, we get the feeling Asus rushed like mad to get the tablet to market in time for the holiday 2011 shopping season. They largely missed that shipping mark, and forums list complaints with poor Wi-Fi performance, Bluetooth interfering with Wi-Fi reception, light bleed and the obvious lack of solid standalone GPS functionality. The tablet can find you in Google Maps just fine if WiFi is turned on and location-based services work, but our Primes can only lock onto satellites when standing stationary outdoors and lose fix in a moving car.

We held back on a full written review so we could test several retail purchased Transformer Prime tablets from different batches and get a handle on how pervasive these problems are. After a month of Prime time, we still think the tablet is worth buying, and it is the fastest, thinnest and lightest Android tablet (for now!). The display is simply marvelous and the outdoor brightness setting is a treat. The feature to price ratio is excellent, and what geek can resist 4 processing cores plus a low power fifth companion core?

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That's not to say our Transformer Primes have been perfect. The first earned the nickname "Chucky", after the possessed evil toy. It took Voodoo to get HDMI working. In fact, the first Prime never output stereo audio to a variety of HD TVs and a late model Sony AV receiver. We bought 3 micro HDMI to HDMI cables to make sure it wasn't a cable issue. We rebooted everything ad infinitum, and still only got left channel audio. Perhaps it was a bad micro HDMI port. Our latest Prime outputs stereo to our Samsung and Insignia HD TVs but we get no sound or detection of audio signal from our Sony AV receiver. Close enough... maybe. With Chucky, the glorious rear 8MP camera took photos and videos that looked like camera phone circa 1998 (grainy, unfocused and overexposed). So did the second (from the same batch). Final Prime takes wonderful photos and video.

Chucky the Prime had a bad case of light bleed. Light bleed, or too much illumination along one or more edges is a common problem with tablet panels, but this was distractingly bad and the black bars in HD videos glowed ghostly light gray. Our second and final Primes have only very minor light bleed that's no worse than that paragon of quality, the iPad 2.

Chucky had great WiFi though, with no precipitous drop off of signal or throughput. And he was happy to stream audio to Bluetooth stereo speakers while watching streaming Netflix video over WiFi. Our latest Prime had problems with drop off when moving 20 feet from the router and we lost 30% of throughput when the tablet was also actively connected to a Bluetooth game controller or stereo speakers/headphones (keyboards didn't affect it, but involves much less data transmission). So we squeezed the Prime to improve the antenna connections, and voila: WiFi improved and our MIA GPS appeared (see the Squeezy Prime section below).

So our final Prime got the name Squeezy Prime, and WiFi now works as well as other tablets, though Bluetooth still reduces throughput (not a problem with our fast 25Mbps connection, but 4Mbps or lower services like DSL would be). Squeezy Prime has no light bleed, no dead pixels, no creaks or separation and I've decided he's a keeper. Out of the box, the GPS would not find a single satellite, not even outdoors after 15 minutes of searching. But the squeeze got us 12 to 14 satellites in view and a lock on 8. He's no navigation wizard, but I don't plan to use a 10" WiFi-only tablet for in-vehicle navigation.

Design and Ergonomics

The Asus Eee Pad Transformer Prime is the first Android tablet that can really take on the iPad 2 in terms of design, materials and looks. Some might say it's even better looking than the iPad 2 thanks to eye-catching swirled metal pattern back and razor-thin edges. That aggressive taper is a double-edge sword though, because the tablet can dig into palms and make it hard to grip. At some point, a consumer electronics device can be too thin, believe it or not. I personally find the iPad 2 uncomfortably thin too. The Transformer Prime's glass front and metal back are slippery too, so you might want a case. In fact, that seemingly durable metal back can be scratched, so you really need a case. The front is Gorilla Glass for durability and scratch resistance. The extreme side taper means that ports aren't well supported (half the micro HDMI, docking port and even the microSD card slot are shallow with little to support the port and cable). The microSD card sticks out just a tiny bit beyond the casing, and we've accidentally ejected the card a few times. The tablet has haptic feedback, a less common feature in 10" tablets that we appreciate.

The Transformer Prime uses the same docking/syncing/charging port and charger as the last generation Transformer, and it has a micro HDMI port, microSD card slot and a 3.5mm headphone/mic jack. The power button is on the top edge at the left end (when held in landscape mode) and it's tiny and hard to press (thanks to that very thin side and taper). The volume controls are on the upper left side and are a bit easier to operate. Visually, the Transformer Prime is a beauty, but it's ergonomically challenged.

Much has been said of the metal back and how it may interfere with WiFi, GPS and Bluetooth reception. The wireless antennas run under the display bezel and are not located against the metal back cover, so we're not going to pick on the metal back and its lack of plastic antenna windows. However, we're a little less certain about the connection method used for those antennas. The Prime has 3 pogo pins that connect the two WiFi antennas and single GPS antenna to the motherboard and wireless chips. These seem less than reliable as we noted when we pressed the connection areas to improve our WiFi and GPS reception.

Above: extreme closeup of a pogo pin.

Our latest Prime, "Squeezy Prime", is a 64 gig gray model from the newest back with a "C" serial number. It couldn't see a single satellite outdoors under open sky. It was MIA. WiFi reception was weak and the signal dropped considerably as we moved 15 feet from the router and throughput dropped from 25Mbps down (our rated fiber connection speed), to just 4Mbps when 20 feet away (only one partial wall made of wood and sheetrock in between). Rats. I'd checked out Anandtech's Teardown of the Prime and noticed that the tablet uses pogo pin connectors. They're like tiny pogo sticks that spring up to make contact with copper tape on the main board. They're used in places with little available space (like skinny Prime tablets) and make opening the casing easier (no wires to rip out). What if these didn't fully extend and make contact when the back plate was affixed via compression tabs and a little glue? There'd be signal loss. A-hah!

So I pressed along the top edge black bezel (when held in landscape mode) to see if I could get better contact on the two pogo pins for the diversity WiFi antenna and the closer to center one for the GPS. Don't press like you're trying to see if the Gorilla Glass can be cracked! But do press with enough force to see a little temporary light bleed from the display. Use care: I warned you so don't blame me if you hurt your Prime (not trying to scare you, but we have to cover our butts). The result? The tablet gained 15 db of WiFi signal and had normal throughput that matched some of our other tablets and phones. It's still not the strongest signal among mobile devices, but it's now within normal range. I took the tablet outdoors and the tablet saw 12 satellites with 8 in use in 30 seconds according to an app called GPS Test. That doesn't mean the tablet is great in a moving car, but if you've got a seemingly DOA GPS, this fix just might bring it to life.

Note, that you should judge WiFi not by bars but with an app that's more precise like WiFi Analyzer (free). It will show you your signal in db and also let you know if your access point is on the same channel as others nearby. And you can use the Speedtest.net app to check your upload and download speeds.

Here's a video where I show you where to press and how to press.

Display

Wow, this is a great display. At a standard 1280 x 800 it doesn't break new ground in terms of resolution, but it's a high quality IPS panel that's very sharp, has excellent contrast, accurate colors and extreme brightness. There's a Super IPS+ mode that runs the display at super brightness, and Asus claims 600 nits brightness, which means you can see it outdoors despite glare. The last gen Transformer had a just OK IPS display with less accurate colors and significantly lower brightness. Viewing angles are the usual for IPS: 178 degrees. There's no need to angle the tablet just right to enjoy the display in all its glory. Blacks are deep when watching videos and viewing photos.

Performance

Remember when the first quad core PCs came out and everyone argued whether 4 cores were better than 2 really fast cores? Get ready for that to happen again with mobile OS tablets. Will the new ARM Cortex A15 dual core 28nm CPUs be better or faster than the Tegra 3 T33 that uses the older ARM Cortex A9 40nm CPUs? We won't know until tablets like the upcoming Lenovo Android tablet ship with the new dual core A15 chipset. In the meantime, the Nvidia Tegra 3 is looking good. It's a 4 core CPU (4 A9 cores) that can run a single core up to 1.4GHz, or multiple cores at 1.3GHz according to Nvidia. And there's a fifth companion core that's very low power to handle background tasks and simple things like music playback. Thus the Tegra 3 is very power-frugal by today's standards, and the Transformer Prime can run as long as an iPad 2. The Tegra 3 has a 12 core GeForce GPU built-in for serious gaming and the tablet can handle 3D video playback to a 3D HD TV and 3D gaming when connected to an HD TV via HDMI. It also supports 5.1 channel audio output over HDMI, though the user settings for that and 3D have disappeared with the ICS upgrade.

Running Android OS 3.2 Honeycomb, benchmark apps reported a max clock speed of 1.4GHz, but running Android 4.0 Ice Cream Sandwich, the same apps reported 1.6GHz. Why and which is it? We don't know. Nvidia originally planned the Tegra 3 to run at 1.6GHz, but scaled back clock speed to get better manufacturing yields. It's interesting that benchmark numbers fell a little bit with the upgrade to ICS (the same is true for the Motorola Xoom). With the updated version of Quadrant that offers better multi-core testing, the Prime did quite well, beating most tablets by 33% or more. It did extremely well in AnTuTu and in 3D benchmarks like GLBenchmark and NenaMark2. Independent of GPU and 3D tests, a quad core CPU should perform 25% faster than a dual core CPU using the same cores. From the 3D tests, it's safe to say that the GPU in the Tegra 3 is indeed significantly faster than the Tegra 2's GPU, and it largely outperforms the PowerVR GPU used in the current 1.2GHz TI chipset used in tablets like the Motorola XYBoard 10.1.

Does the Prime feel fast? Yes it does. Does it feel faster than other Android 10" tablets? Yes. But you won't notice worlds of difference when navigating home screens or swiping through the app drawer. We notice it when doing something as simple as flipping pages in the Nook ebook reader app (the Prime flips pages much more quickly, and yes the screen is good for reading). More demanding games like GTA III play smoothly with none of the artifacting we see in 1GHz dual core Android tablets from 2011. There's none of that block-style redraw in the web browser (though ICS does a good job of banishing it on the Xoom too). Web pages load faster. We hope that as more apps and the OS itself make use of 4 cores and more threads, that speed increases will abound.

Asus provides power management and speed settings much like a laptops: there's power saving mode for low power and lower performance, balanced mode where the CPU runs at 1.2GHz max and performance mode that runs the CPU at full speed. There's little difference experientially between standard and performance modes, so it looks like Asus' software does a good job of scaling up when needed. Eco mode feels slow, but is a great way to get more runtime when the tablet's charge is low and you're not near an outlet.

Like most Honeycomb tablets, the Asus Eee Pad Transformer Prime has a gig of RAM. It's available with 32 or 64 gigs of internal storage, and there's a microSD card slot for additional storage. In both Honeycomb and ICS the tablet nicely integrates microSD cards and USB storage into apps like Gallery and Music, so Asus has done their piece with drivers well. The Prime's internal storage isn't benchmarking well, but that's something that might be remedied with a firmware update.

Android OS 4.0, Ice Cream Sandwich

Asus has always impressed us with their fast OS updates and firmware tweaks to fix issues. The original Transformer was always one of the first to get OS updates, and the Prime is the first to get Ice Cream Sandwich, which was probably a feat since the dual core 1.2GHz TI OMAP is the reference CPU for ICS rather than the Tegra 3. Asus launched the upgrade in early January 2012, and then released a revised version about a week later. These are free downloadable updates, and the Prime will let you know when they're available to download and install. Squeezy Prime got the second (and currently latest) ICS build on first boot, so that was a clean install with no legacy app installs or prefs on board. I told the tablet to not automatically install every app from my Google account to the tablet, so I could pick and choose the ones I wanted and avoid possible incompatibilities. As it turns out, that clean install was the ticket to a stable tablet, and the Prime runs quickly and smoothly under ICS. My apps have worked (and I have a lot of apps installed, including 3D games), and I've only seen a momentary freeze twice in 2 weeks.

Keyboard Dock

Part of the appeal of the Asus Eee Pad Transformer Prime (beyond that quad core CPU, ICS and super bright IPS display!) is the optional keyboard dock. For those who want to use the tablet as a notebook replacement for basic tasks like web, email, social networking, video and MS Office work, the $149 keyboard dock sets the original Transformer and the new Transformer Prime apart from the slabbish crowd.

The principle is the same as with the original Transformer and its dock: insert the tablet into a channel at the back of the keyboard and it locks in. It's a firmer connection thanks to two robust tabs that slide into the tablet, but you still shouldn't pick up and carry the open "laptop" by the display section because it might not hold. Note that you'll have to remove the two rubber plugs at the bottom of the tablet with a paperclip: those plugs cover the channels where the docking station tabs insert.

The dock has a keyboard, trackpad, 1 USB 2.0 port that works with USB peripherals (we tested flash drives, hard drives, USB game controllers and USB Ethernet adapters), a full size SD card slot and a charging/dock connector. There's 22Wh battery inside that charges the tablet and adds approx. 6 hours to battery life. As with the later revision of the original Transformer dock, you can set the dock to sleep when the display is off so the dock battery isn't drained unnecessarily. When the Transformer Prime is in the dock, it will charge itself from the dock and deplete the dock battery before using its own battery. Asus includes a widget that shows you the status of the tablet and dock batteries.

The package looks very attractive and is noticeably more compact and lighter than the original Transformer and dock combo. The keyboard dock is clad in matching aluminum, and comes in champagne and gray to match the tablet colors (make sure you order the right color!). The Transformer Prime with dock in laptop mode is considerably smaller than today's 13.3" Ultrabooks, and at 2.5 lbs. is lighter than all Ultrabooks except the 2.5 lb. Toshiba Portege Z830.

The tablet weighs 1.3 lbs. while the keyboard dock weighs 1.2 lbs.; but I don't find the combo to be top heavy (the weights are very close). I've used it several days at a variety of locations and angles and it's stable. Rubber feet on the dock's bottom give it a good grip, and when opened beyond upright, the rear rests on the large barrel hinge that holds the tablet.

Five cores doesn't mean bad battery life. Quite the opposite, that fifth companion core and good power management mean that the Asus Transformer Prime can go 8 hours with WiFi on and brightness set to 33% (which is actually quite bright for indoor use). As with most tablets, the 25Wh Lithium Ion battery is sealed inside. The tablet charges very quickly.

Conclusion

The Asus Eee Pad Transformer Prime is currently the thinnest, lightest and arguably fastest tablet (the iPad 2 is faster on some OpenGL graphics benchmarks). We love the looks, the attention to detail in manufacturing (no creaks, no gaping seams, perfectly smooth edges and ports) and the look of the swirled aluminum back. Coupled with the keyboard dock, it's truly a beauty to behold and gloriously compact. The Super IPS+ display has great colors, excellent contrast and is extremely bright. Battery life is very good and with the dock, it can manage 12 hours of real life use. For the price, the Transformer Prime offers top notch specs, and the only missing option is 3G/4G.

The caveat is the GPS that isn't good enough for navigation on the road, and the WiFi reception issue that seems fairly common. Yes, in our case a squeeze got WiFi working up to snuff, but really should you have to squeeze your tablet to get standard features working? And was it kosher that Asus removed the GPS from the specs list on their website after users complained the GPS didn't work well for navigation? Nope.